CN112119300B - PH measurement of water samples - Google Patents

Abstract

A method and apparatus for measuring pH in a water sample using a glass-free membrane electrode, comprising: introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, preferably an sp3 boron doped diamond electrode that is sensitive to interferents and insensitive to pH, and wherein at least one of the at least three electrodes comprises a second measurement electrode, preferably an sp2/sp3 boron doped diamond electrode that is sensitive to pH and interferents; measuring a first potential between a first measurement electrode and a ground rod electrode in the water sample; measuring a second potential between a second measurement electrode and a ground rod electrode in the water sample; and identifying the pH of the water sample based on the difference between the first potential and the second potential.

Description

PH measurement of water samples

Technical Field

The present application relates generally to pH measurement of water samples, and more particularly to pH measurement using electrodes without glass films and internal reference solutions.

Background

Ensuring water quality is critical to the health and well-being of water-dependent living humans, animals and plants. One parameter of water that can be measured is pH. Measurement of the pH of water samples is critical in many industries such as pharmaceutical, biomedical, water supply and other manufacturing fields. The measurement of pH may allow for proper treatment of the water or ensure proper water quality for sensitive purposes and allow for the identification of the overall quality of the water. One method for measuring pH in a water sample involves the use of electrodes that require constant maintenance and calibration of the pH measurement system.

Disclosure of Invention

In summary, one embodiment provides a method for measuring pH in a water sample using a glass-free membrane electrode, comprising: introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode; measuring a first potential between a first measurement electrode and a ground rod electrode in the water sample; measuring a second potential between a second measurement electrode and a ground rod electrode in the water sample; and identifying the pH of the water sample based on the difference between the first potential and the second potential.

Another embodiment provides a measurement apparatus for measuring pH in a water sample using a glass-free membrane electrode, comprising: at least one chamber; one or more series of electrodes disposed at least partially within the at least one chamber; a processor; and a memory device storing instructions executable by the processor to: introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode; measuring a first potential between the first measurement electrode and the ground rod electrode in the water sample; measuring a second potential between the second measurement electrode and the ground rod electrode in the water sample; and identifying the pH of the water sample based on the difference between the first potential and the second potential.

Yet another embodiment provides a product for measuring pH in a water sample using a glass-free membrane electrode, comprising: a storage device storing code, the code being executable by a processor and comprising: code for introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode; code for measuring a first potential between a first measurement electrode and a ground rod electrode in the water sample; code for measuring a second potential between a second measurement electrode and a ground rod electrode in the water sample; and code for identifying the pH of the water sample based on the difference between the first potential and the second potential.

The foregoing is a summary and thus contains, by necessity, simplifications, generalizations, and omissions of detail; accordingly, those skilled in the art will appreciate that this summary is illustrative only and is not intended to be in any way limiting.

For a better understanding of the embodiments, together with other and further features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings. The scope of the invention will be pointed out in the appended claims.

Drawings

Fig. 1 shows an example of a computer circuit.

Fig. 2 shows a flow chart for measuring pH in a water sample.

FIG. 3 shows a schematic of measuring pH in a water sample in an example embodiment.

FIG. 4 shows an example measurement for determining the pH of a water sample.

Fig. 5 shows an example of differential pH internal references in a water sample.

Fig. 6 shows example data for differential pH internal references in a water sample.

FIG. 7 illustrates an example circuit with reference offset cancellation for pH measurements in a water sample.

FIG. 8 illustrates another example circuit with reference offset cancellation for pH measurements in a water sample.

Detailed Description

It will be readily understood that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations in addition to the exemplary embodiments described. Thus, the following more detailed description of the example embodiments, as represented in the figures, is not intended to limit the scope of the embodiments, as claimed, but is merely representative of example embodiments.

Reference throughout this specification to "one embodiment" or "an embodiment" (or the like) means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" or the like in various places throughout this specification are not necessarily all referring to the same embodiment.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the various embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail. The following description is intended to simply illustrate certain exemplary embodiments by way of example only.

Measurement of the pH of water or other aqueous solutions or samples is very common and allows determination of the quality or other characteristics of the aqueous solution. Conventional pH measuring instruments are available; however, these instruments are complex and require constant maintenance and calibration. For example, conventional pH measurements use pH electrodes that are introduced into the water sample. To measure the pH of a sample, the pH electrode includes an internal solution that serves as a reference for measurements made within the water sample. Thus, conventional pH measurement devices require a user to manually add an internal solution to the electrode.

The internal solution used in conventional pH measurement electrodes is typically a high molar potassium chloride solution. Many pH electrodes contain a fill port for the internal or reference solution that must be closed to prevent evaporation of the reference solution. Not closing the port causes evaporation and increases the molar concentration of the internal reference solution. An increase in molar concentration can alter the sensitivity of the pH electrode and also cause crystallization of salts in the pH electrode, thereby damaging the electrode.

In addition, conventional pH electrodes comprise a glass membrane (fret). The glass film acts as a conductive "core" between the electrode filling solution and the water sample to be measured. The glass membrane allows electrical conduction while maintaining the internal solution and water sample in separate volumes. The glass film requires maintenance, for example, cleaning the glass film to prevent scaling. If the glass film fouls, the electrode will need to be recalibrated and maintained. In addition, the glass film is easily dried. Therefore, conventional pH measurement electrodes need to be stored in an aqueous environment to minimize damage to the electrode by allowing the glass film to dry. Failure to maintain proper internal solutions or glass films can damage the pH electrode, reduce sensitivity, or render the electrode inoperable. In addition, the glass film and the fill solution can result in a junction potential (junction potential) that can affect the measurement of the pH electrode.

In addition, conventional pH electrodes may be constructed using thin, brittle glass. Such glasses are prone to breakage, resulting in higher replacement and maintenance costs. Conventional pH electrodes may also have "alkalinity errors". These errors are caused by interfering ions (e.g., sodium and lithium) that affect the pH response at high pH values. What is needed is a pH measurement electrode that requires less maintenance while maintaining the sensitivity of the pH measurement.

Thus, the systems and methods described herein provide techniques for pH measurement using electrodes without glass films and without internal solutions that are capable of measuring electrical signals and identifying portions of the electrical signals that are attributed to interferents and the electrical signals that are the result of the pH of a water sample. In particular, the systems and methods described herein can identify the potential of a water sample using an electrode that is sensitive to interferents and an electrode that is sensitive to both interferents and the pH of the water sample. In other words, in embodiments, the electrodes may be materials that are sensitive to interferents, and/or the pH of interferents and water samples. For example, the electrodes may include Sp2 and/or Sp3 carbon materials, which may comprise diamond-like materials (BDDs) doped with boron-like elements. In this case, the first electrode would comprise a localized microelectrode or nanoelectrode array of SP2 carbon on the SP3 substrate that would be sensitive to interferents and pH, while the second electrode would comprise an SP3 substrate that would be sensitive to interferents only. Other materials may include metal systems, in which case the first electrode would include localized iridium oxide microelectrodes or nanoelectrodes on the conductive iridium metal substrate that would be sensitive to both pH and interferents, while the second electrode would include only iridium metals that would be sensitive to interferents only.

Other proton sensitive/insensitive metal oxide/metal systems include tin, tungsten, palladium, rhodium, platinum, osmium, tantalum, vanadium. Other proton-sensitive/insensitive carbonaceous systems include modified CNTs, graphene nanocellulose. By incorporating silicon oxide micro/nanostructures on a conductive or semiconductive silicon substrate, a first electrode glass system that is sensitive to interferents and pH can be achieved. The second electrode will only comprise a silicon substrate without any silicon oxide that will be sensitive to interferents and not to pH, which will be a reference-free glass electrode. By making both measurements, the system can subtract the measurement due to the interferent from the overall measurement and then identify the pH of the water sample. To make these measurements, the system may include a common ground electrode or a reference electrode. Thus, the method can use the measured sequence as a means of quantifying the interfering substances.

BDD is used as a better electrode material than other carbon-based or metallic materials (e.g., silver, gold, mercury, nickel, etc.), as these carbon-based or metallic materials may eventually oxidize themselves, thereby creating interfering signals and causing errors in the measurement of pH. The thin film BDD electrodes may be subject to thermal stress due to the different coefficients of thermal expansion between the substrate and BDD layers, which limits the current density that can be applied to these electrodes. Thick BDD solid state electrodes have no substrate and therefore can maintain structural and electrical integrity at higher currents. The absence of a substrate in a thick solid state independent BDD electrode eliminates the delamination problem that may occur on thin film BDD materials. Thus, the electrodes used in the measuring device may be thick film BDD electrodes.

In an embodiment, a water sample may be introduced into the measurement chamber. Alternatively, the pH measuring device may be incorporated into the water sample. A first potential measured between the first electrode and the ground electrode may be measured. The first potential may be due to the amount of interferents (measure) in the water sample. A second potential measured between the second electrode and the ground electrode may also be measured. The ground electrode associated with the measurement of the second potential may be the same as the ground electrode used in the measurement of the first potential. The second potential may be associated with both the interferent and the pH of the water sample. In an embodiment, the first potential and the second potential may be subtracted to remove the measured interferent component to identify the pH of the water sample. Thus, the method may mathematically consider the interferents by using two or more electrical responses to remove charge transferred to the interferents that may lead to erroneous pH identification without using electrodes comprising glass membranes or internal reference solutions.

The example embodiments shown will be best understood by reference to the accompanying drawings. The following description is intended to simply illustrate certain exemplary embodiments by way of example only.

While various other circuits, circuitry, or components may be used in an information processing device, an example is shown in fig. 1 for an instrument for pH measurement in accordance with any of the various embodiments described herein. The device circuitry 100 may include a measurement system on a chip design build (e.g., a particular computing platform (e.g., mobile computing, desktop computing, etc.)). The software and processor are combined into a single chip 101. Processors include internal arithmetic units, registers, caches, buses, I/O ports, etc., as is well known in the art. Internal buses and the like are dependent on different suppliers, but virtually all peripheral devices (102) may be attached to a single chip 101. The circuit 100 combines a processor, memory control, and I/O controller hub into a single chip 110. Furthermore, this type of system 100 typically does not use SATA or PCI or LPC. Common interfaces include, for example, SDIO and I2C.

There is a power management chip 103, e.g. a battery management unit BMU, which manages the supplied power, e.g. by means of a rechargeable battery 104, which rechargeable battery 104 can be recharged by connection to a power source (not shown). In at least one design, a single chip such as 101 may be used to provide both BIOS-like functionality and DRAM memory.

The system 100 typically includes one or more of a WWAN transceiver 105 and a WLAN transceiver 106 for connection to various networks (e.g., telecommunications networks) and wireless internet devices (e.g., access points). In addition, devices 102 are typically included, such as transmit and receive antennas, oscillators, PLLs, and the like. The system 100 includes an input/output device 107 for data input and display/rendering (e.g., a computing location located remotely from the single beam system that is easily accessible by a user). The system 100 also typically includes various memory devices, such as flash memory 108 and SDRAM 109.

It will be appreciated from the foregoing that the electronic components of one or more systems or devices may include, but are not limited to, at least one processing unit, memory, and a communication bus or means for coupling the various components, including memory, to the processing unit. The system or device may include or access various device readable media. The system memory may include device readable storage media in the form of volatile and/or nonvolatile memory such as Read Only Memory (ROM) and/or Random Access Memory (RAM). By way of example, and not limitation, system memory may also include an operating system, application programs, other program modules, and program data. The disclosed system may be used in embodiments to perform pH measurements of water samples.

Referring now to fig. 2, an embodiment may use a glass-free membrane electrode that does not require an internal reference solution to measure pH in an aqueous solution. In other words, these electrodes do not need to be filled with a solution, a glass film, and are made of materials other than the brittle thin glass of conventional electrodes. The systems and methods described herein provide techniques for avoiding pH measurement of interferents that can be used in practice with actual water samples without the need for recalibration and maintenance required by conventional systems, as components responsible for maintenance requirements and calibration are eliminated.

At 201, in an embodiment, a measurement device may be introduced into a water sample. Alternatively, a water sample may be introduced into a test chamber, for example a test chamber of a measurement device. If a water sample is introduced to the measurement device, the water sample may be placed or introduced into the test chamber manually by the user or using mechanical means (e.g., gravity flow, pump, pressure, fluid flow, etc.). For example, a water sample for pH testing may be introduced into the measurement or testing chamber using a pump. In embodiments, valves or the like (if present) may control the inflow and outflow of aqueous solution into and out of one or more chambers. Once the sample is introduced into the measurement system, the system can use the steps described in more detail below to measure the pH of the sample. In an embodiment, the measuring device may comprise one or more chambers, wherein one or more method steps may be performed.

The measurement device may comprise at least three electrodes for measuring the pH of the water sample. Thus, embodiments may include a first measurement electrode, a second measurement electrode, and a ground (reference) electrode. The ground electrode may be shared by the first and second measurement electrodes. In other words, both the first and second measurement electrodes may be electrically connected to a ground or reference electrode, and the ground or reference electrode may be used by both measurement electrodes to implement an electrical circuit. In embodiments, one or more of the measurement electrodes may be composed of the same or different materials. For example, one measurement electrode may be composed of a material that is insensitive to analyte (e.g., sp 3/pure phase boron doped diamond material), while a second measurement electrode may be composed of a material that is sensitive to analyte (e.g., sp2/Sp3 boron doped diamond or other carbon material).

In an embodiment, the electrodes may be disposed entirely or at least partially in the volume of the aqueous solution. For example, if an aqueous solution is introduced into a chamber having one or more electrodes, the aqueous solution may at least partially cover the one or more electrodes. As another example, one or more electrodes may be partially disposed within the chamber, with other portions of the electrodes being external to the chamber. Thus, when an aqueous solution is introduced into the chamber, it covers only the portion of the electrode within the chamber.

At 202, in an embodiment, the system may measure a first potential of a volume of the aqueous solution in the chamber by applying an electrical signal between the first measurement electrode and the reference electrode. The use of the terms "first" or "second" is not intended to indicate a time indication of when a measurement is made or the position of one electrode relative to the other. In contrast, the terms "first" and "second" are used only to distinguish between two different electrodes.

One or more electrodes (e.g., a series of electrodes) may be used or an electrical signal may be applied to one or more electrodes. In an embodiment, the first measurement electrode may be used to measure the potential due to any interferents in the water sample. Thus, the first measurement electrode may be composed of a material that is insensitive to analyte (e.g., sp3 Boron Doped Diamond (BDD) electrode material). The Sp3 BDD electrode may be alumina polished. The Sp3 BDD electrode may be pure phase. The Sp3 BDD electrode may be polarized, for example, using an electrochemical process, to provide a uniform, clean, and homogenous substrate. This can be done in 0.1m h2so4 at 3V for 60 seconds. The Sp3 electrode may be insensitive to pH measurements only. The particular pH insensitivity of the Sp3 BDD electrode may be due to the pH response of the electrode being within 4mV-5 mV/pH. Thus, this type of material is useful for measuring pH independent potentials. Thus, the resulting potential measurement can be attributed to any interferents in the water sample. Applying an electrical signal between the first electrode and the ground electrode allows measuring a first potential that can be measured between the first measurement electrode and the ground electrode.

At 203, in an embodiment, the system may measure a second potential of the volume of the aqueous solution in the chamber by applying an electrical signal between the second measurement electrode and the ground electrode. The ground electrode for the second measurement may be the same as the ground electrode for the first measurement to ensure that the measurements are consistent and reference the same measurements. In other words, the use of a single ground electrode accounts for any noise or electrical imperfections that may be attributed to the ground electrode itself. As with the first measurement, one or more electrodes (e.g., a series of electrodes) may also be used to apply the electrical signal for the second measurement.

In an embodiment, the second measurement electrode may be composed of a material that is sensitive to the analyte (e.g., sp2/Sp3 Boron Doped Diamond (BDD) electrode material). In embodiments, a controlled amount of Sp2 carbon (e.g., a non-diamond material, such as a glassy carbon comprising Sp2 carbon, etc.) may be introduced into or onto the Sp3 BDD carbon, thereby forming an Sp2/Sp3 BDD electrode. For example, sp2 carbon may be introduced into an Sp3 BDD electrode using laser patterning, resulting in a polycrystalline boron doped diamond material that exhibits the advantages of a glassy carbon electrode for pH measurement while generating a low base flow due to the BDD substrate (background current). The measurement of pH can be achieved by introducing Sp2 carbon into the Sp3 BDD carbon. Thus, in contrast to the Sp3 BDD electrode, the Sp2/Sp3 electrode may be pH sensitive. Thus, the Sp2/Sp3 electrode may be sensitive to both interferents and pH. The introduction of Sp2 may result in an electrode that may be subjected to a pH assay having a sensitivity of 58mV/pH +/-5 mV. Since the second measurement electrode is sensitive to the analyte, the potential measured between the second measurement electrode and the ground electrode is due not only to the interferents in the sample, but also to the pH of the sample.

In an embodiment, the first and second measurement electrodes may be used to measure the potential in the aqueous solution with reference to a ground electrode (ground rod or reference electrode). The ground electrode may be the same for both the first and second measurement electrodes. The use of a single ground rod and multiple measurement electrodes can compensate for potential, conductivity, oxidation-reduction potential (ORP), etc. in multiple potential measurements of a water sample. The ground electrode may comprise or be made of titanium (Ti), platinum (Pt), or any other conductive metal that may not be susceptible to scaling. In an embodiment, the one or more series of electrodes may be Boron Doped Diamond (BDD) electrodes.

At 204, the system may determine or identify the pH of the water sample. To make this determination, the system may subtract the potential associated with the interferents of the water sample from the potential associated with the interferents and pH to give the pH of the resulting water sample. For example, the open circuit potential measured from the Sp3 BDD material may be the potential associated with the disturbance minus the ground potential. The open circuit potential measured from the Sp2/Sp3 material (BDD, glassy carbon, etc.) may be the potential associated with both pH and interferents. Thus, in this example, to identify the potential due to the pH of the sample, the measured potential measured at the first measurement electrode may be subtracted from the measured potential measured at the second measurement electrode. For example, referring to fig. 4, voltammetry for determining pH measurements may be used. For example, voltammetric scans may be initiated from an open circuit potential for each water sample. The difference between the peak potential and the starting potential may identify a correlation of the peak (dependence). The differential potential between the measured open circuit potential and the peak potential may eliminate the floating nature of the ground electrode itself. Examples of methods can be found in fig. 5 and 6.

If the system is unable to identify the pH of the aqueous solution, the system may continue to measure the electrical response from the electrodes of the system at 202. Additionally or alternatively, the system may trigger an alarm, shut down, change the flow control of the water sample, etc. However, if the pH of the water sample can be determined at 205, the system can output the pH of the aqueous solution. The output may be in the form of a display, storing data to a memory device, transmitting output through a connected system or wireless system, printing output, etc. The system may be automated, meaning that the system may automatically output the identified pH. The system may also have an associated alarm, limit, or predetermined threshold. For example, if the measured pH reaches a threshold, the system may trigger an alarm, adjust the pH of the aqueous solution, change the flow of the aqueous solution, and so forth. The data may be analyzed in real-time, stored for later use, or any combination thereof.

Referring to fig. 7 and 8, the circuit may control the electrical signals and/or measurements (e.g., current, voltage, etc.) of one or more series of electrodes such that different electrical signals may be applied and/or measured for the volume of aqueous solution. In an embodiment, the first and second measurement electrodes may be connected to a solid state differential pH measurement circuit with an internal reference. Where multiple or a series of electrodes are included in the system, each electrode may correspond to a different electrical signal value. For example, a first electrode may correspond to a first electrical signal value, a second electrode may correspond to a second electrical signal value, and so on. Each of these different electrical signal values may provide an electrical signal that will measure the interferents and/or pH of the water sample. Thus, as the system sequentially provides an electrical signal to each of the electrodes, the system may apply a different electrical signal or measure a different electrical signal at a single electrode. In each case, the system may measure the pH of the aqueous solution after each application of the electrical signal. Other electrodes may be included to implement circuitry or to provide a reference electrode (e.g., a ground electrode, a plurality of measurement electrodes, etc.) for measurement. The circuits of fig. 7 and 8 are example embodiments and are not meant to be limiting. The circuit of fig. 7 shows an example embodiment for BDD voltammetry in combination with reference offset cancellation. The circuit of fig. 8 shows an example embodiment for BDD voltammetry in combination with differential measurement of quiescent potential and response current.

As will be appreciated by one skilled in the art, aspects may be embodied as a system, method or apparatus program product. Thus, the aspects may take the form of entirely hardware embodiments, or embodiments including software, which may be referred to generally herein as a "circuit," module, "or" system. Furthermore, aspects may take the form of a device program product embodied in one or more device-readable media having device-readable program code embodied therewith.

It should be noted that the various functions described herein may be implemented using instructions stored on a device-readable storage medium, such as a non-signal storage device, where the instructions are executed by a processor. In the context of this document, a storage device is not a signal and "non-transitory" includes all media except signal media.

Program code for carrying out operations may be written in any combination of one or more programming languages. Program code may execute entirely on a single device, partly on a single device, as a stand-alone software package, partly on a single device and partly on another device or entirely on other devices. In some cases, the devices may be connected through any type of connection or network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made through other devices (e.g., through the internet using an internet service provider), through a wireless connection (e.g., near field communication), or through a hard-wired connection (e.g., through a USB connection).

Example embodiments are described herein with reference to the accompanying drawings, which illustrate example methods, apparatus and articles of manufacture according to various example embodiments. It will be appreciated that acts and functions may be implemented, at least in part, by program instructions. These program instructions may be provided to a processor of a device (e.g., a handheld measuring device such as that shown in fig. 1, or other programmable data processing apparatus for producing a machine) such that the instructions, which execute by the processor of the device, implement the specified functions/acts.

It is noted that the values provided herein are to be construed as including equivalent values indicated by the use of the term "about". Equivalent values will be apparent to those skilled in the art, but include at least values obtained by the usual rounding of the least significant digits.

The present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limiting. Many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to explain the principles and practical application, and to enable others of ordinary skill in the art to understand the various embodiments of the present disclosure for various modifications as are suited to the particular use contemplated.

Thus, although illustrative example embodiments have been described herein with reference to the accompanying drawings, it is to be understood that such description is not limited, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure.

Claims (16)

1. A method for measuring pH in a water sample using a glass-free membrane electrode, comprising:

Introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode, wherein the second measurement electrode comprises a material that is sensitive to analytes and interferents, wherein the first measurement electrode comprises Sp3 boron doped diamond material;

measuring a first potential between the first measurement electrode and the ground rod electrode in the water sample;

measuring a second potential between the second measurement electrode and the ground rod electrode in the water sample; and

The pH of the water sample is identified based on the difference between the first potential and the second potential.

2. The method of claim 1, wherein the first measurement electrode comprises a material that is insensitive to analytes and sensitive to interferents.

3. The method of claim 1, wherein the second measurement electrode comprises Sp2/Sp3 boron doped diamond material.

4. The method of claim 1, wherein the first potential is due to an interferent in an aqueous solution.

5. The method of claim 1, wherein the second potential is due to both an interferent in the aqueous solution and the pH of the aqueous solution.

6. The method of claim 1, wherein the identifying comprises subtracting the second potential from the first potential.

7. The method of claim 1, wherein the method does not require a glass film or a reference solution.

8. The method of claim 1, wherein the first and second measurement electrodes are in electrical communication with a solid state differential pH measurement circuit having an internal reference.

9. A measurement device for measuring pH in a water sample using a glass-free membrane electrode, comprising:

At least one chamber;

one or more series of electrodes disposed at least partially within the at least one chamber;

A processor; and

A memory device storing instructions executable by the processor to:

Introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode, wherein the second measurement electrode comprises a material sensitive to analytes and interferents, wherein the first measurement electrode is an Sp3 boron doped diamond electrode;

measuring a first potential between the first measurement electrode and the ground rod electrode in the water sample;

measuring a second potential between the second measurement electrode and the ground rod electrode in the water sample; and

The pH of the water sample is identified based on the difference between the first potential and the second potential.

10. The apparatus of claim 9, wherein the first measurement electrode comprises a material that is insensitive to analytes and sensitive to interferents.

11. The apparatus of claim 9, wherein the second measurement electrode comprises Sp2/Sp3 boron doped diamond material.

12. The apparatus of claim 9, wherein the first potential is due to an interferent in an aqueous solution.

13. The apparatus of claim 9, wherein the second potential is due to both an interferent in the aqueous solution and a pH of the aqueous solution.

14. The apparatus of claim 9, wherein the identifying comprises subtracting the second potential from the first potential.

15. The apparatus of claim 9, wherein the first and second measurement electrodes are in electrical communication with a solid state differential pH measurement circuit having an internal reference.

16. A product for measuring pH in a water sample using a glass-free membrane electrode, comprising:

A storage device storing code executable by a processor and comprising:

Code for introducing a water sample into a measurement device comprising at least three electrodes, wherein at least one of the at least three electrodes comprises a grounded rod electrode, wherein at least one of the at least three electrodes comprises a first measurement electrode, and wherein at least one of the at least three electrodes comprises a second measurement electrode, wherein the second measurement electrode comprises a material that is sensitive to an analyte and an interferent, wherein the first measurement electrode is an Sp3 boron doped diamond electrode;

Code for measuring a first potential between the first measurement electrode and the ground rod electrode in the water sample;

Code for measuring a second potential between the second measurement electrode and the ground rod electrode in the water sample; and

Code that identifies the pH of the water sample based on a difference between the first potential and the second potential.